M. TECHNOLOGY. 515 



preferred, although less conveniently employed. According 

 to Yiedt, however, gold, silver, and bronze inks are prepared 

 that afford beautiful results, and that flow freely, though 

 slowly, from an ordinary steel pen, although better applied 

 with a pencil. True gold-leaf, although undoubtedly the 

 best for ink, is sometimes replaced, on account of its price, 

 by mosaic gold or iodide of lead, but generally by false leaf. 

 On account of the cheapness of silver-leaf, silver ink of infe- 

 rior quality is but seldom made from false leaf, etc. Ordi- 

 nary commercial bronze powders are employed for inks of 

 other metallic tints. Besides true and false leaf, metals are 

 to be had in the form of very fine powder, prepared from 

 gold-beater's waste, by rubbing it through sieves. These, 

 previous to the manufacture of ink, must be freed from fatty 

 and other impurities derived from the skins by triturating 

 them or the bronze powders on a glass or porphyry slab 

 with just enough honey to form a thin paste, as carefully as 

 possible, since the beauty of the ink depends greatly upon 

 this operation. This paste is then boiled for some time in a 

 glass beaker, with water rendered somewhat alkaline, and 

 allowed to settle, and, after the liquid is decanted, the pow- 

 der is well washed with hot water, and dried at a gentle 

 heat. Different shades may be imparted to it by boiling it 

 with water containing sulphuric, hydrochloric, or nitric acid. 

 A sufficient quantity of the purified powder is triturated 

 with a solution of one part of white gum-arabic, four of dis- 

 tilled water, and one of potash water-glass. In general, one 

 part of metal to three or four of the liquid will answer, but 

 less gold is required than silver, since it covers far better; 

 and glazed paper, and paper of a dark shade, also require 

 less metal than rough, or light-tinted paper. A stock of ink 

 may be prepared at once, and is best kept in a shallow por- 

 celain vessel, so that it can be thoroughly stirred before 

 filling into smaller bottles. It is also necessary to stir fre- 

 quently when using it, and it is preferable to mix the dry 

 powder with the liquid just before using it. The water- 

 glass plays an important part in increasing the lustre, pro- 

 tecting the tint from atmospheric influences, and preventing 

 too deep a penetration into the paper, without much im- 

 pairing the fluidity. The lustre can also be improved by 

 gentle burnishing. 



